Watercress Tops Ranking of Nutrient-Dense Foods

CDC compiles list of "powerhouse fruits and vegetables."

Step aside, kale and blueberries. According to a new ranking of what it calls "powerhouse fruits and vegetables," the Centers for Disease Control and Prevention says that the humble green watercress is the most nutrient-dense produce item.

Jennifer Di Noia, Ph.D., of William Patterson University in New Jersey, created the ranking by starting with a list of potential produce powerhouses. The initial list was based on literature that identified leafy greens, yellow/orange vegetables, citrus fruits and cruciferous vegetable as being associated with reduced chronic disease, and berry and allium vegetables as being associated with reduced risk for cardiovascular and neurodegenerative disease, and some cancers.

For each of the 47 foods she selected, Di Noia created a nutrient-density score, based on the percentage of recommended daily value of 17 nutrients each contains per 100 grams. The percentage of daily value for each nutrient was capped at 100, so that no one nutrient would outweigh others (and so that a food that's exceptionally high in one nutrient but lacking in many others wouldn't be classified as nutrient-dense). Among the nutrients considered were iron, vitamin C, fiber, zinc and folate.

Each food's score represents the average of percent daily values per 100 calories; the best a food could score was 100. Di Noia counted a food as a powerhouse if it scored 10 or higher.

Using this system, watercress came out on top as the most nutrient-dense fruit or vegetable, with a score of 100. It was followed by Chinese cabbage (91.99), chard (89.27), beet greens (87.08) and spinach (86.43). Kale, with a score of 49.07, ranked 15th. A screen grab of the first part of the nutrient-density ranking is below. The full list is available here.

Six foods Di Noia considered, including blueberries and raspberries, didn't get a "powerhouse" ranking. Berries are often touted for their phytochemical content, or chemical compounds such as antioxidants that are thought to impart health benefits but that aren't considered essential nutrients. "Because it was not possible to include phytochemical data in the calculation of nutrient density scores, the scores do not reflect all of the constituents that may confer health benefits," Di Noia wrote.

The CDC ranking is meant to help guide food choices and to encourage eating a wide variety of nutrient-dense foods, rather than have watercress become the new national food obsession. That said, because many people are relatively unfamiliar with watercress, below are a few watercress recipes to get you started. A full list, as well as recipes for other nutrient-dense foods, are available at the Rodale recipe finder.